* {
  padding: 0;
  margin: 0;
  list-style: none;
  box-sizing: border-box;
}

.box {
  position: relative;
  margin: 50px auto;
  width: 300px;
  height: 300px;
  /* border: 1px solid #000;  */
}

.box > .smallBox {
  width: 300px;
  height: 300px;
  border: 1px solid #000;
  cursor: pointer;
}
.box > .smallBox > img {
  width: 100%;
}
.box > .smallBox > .mask {
  position: absolute;
  left: 0;
  top: 0;
  width: 100px;
  height: 100px;
  background-color: rgba(0, 0, 0, 0.5);
  display: none;
}
.box > .bigBox {
  position: absolute;
  width: 300px;
  height: 300px;
  left: 300px;
  top: 0;
  border: 1px solid #000;
  overflow: hidden;
  display: none;
}

.box > .bigBox > img {
  width: 800px;
  height: 800px;
}
